The permanent alteration of the colour of keratinous fibres, in particular human hair, by the application of hair dyes is well known. In order to provide the consumer with the hair colour and the intensity of colour desired, a very complex chemical process is utilized. Permanent hair dyeing formulations typically comprise oxidative hair dye precursors, which can diffuse into the hair through the cuticle and into the cortex where they can then react with each other and suitable oxidising agents to form the end dye molecules. Due to the larger size of these resultant molecules they are unable to readily diffuse out of the hair during subsequent washing with water and/or detergents; hence delivering a consumer-desired permanency of colour. This reaction typically takes place in an aggressive environment at approximately pH 10 in the presence of an alkalizing agent and in the presence of an oxidizing agent. Moreover, the consumer repeats this process regularly in order to maintain the desired hair colour and shade and the intensity of colour and to ensure continual, even coverage of the hair including coverage of new hair growth.
The manufacturer of such products is also required to work within a large number of constraints. Since these products are being placed in direct contact with the consumers' skin, the potential exists for accidental contact with the eye or for ingestion (for example), which can occur during the dyeing process. Therefore, the formulation must meet rigorous safety requirements and not induce any allergic reactions. In addition to meeting these requirements, the products must also be optically and olfactory pleasing to the consumer. In particular, the products also need to meet certain physical parameters in order to ensure that the product can be easily applied to the hair by the consumer to provide the desired effect, without unintentional staining of the consumers' clothes, skin particularly along the hair line or other objects.
The manufacturer is also required to provide the hair colouring consumer a large range of different resulting colours. Some consumers may just wish to enhance the natural colour of the hair, whilst others may wish to cover grey or completely alter the hair colour to a different natural appearing hair colour or a ‘synthetic’ appearing hair colour. Consequently, the manufacturer may provide well over twenty different formulations, of varying colours and shades, to address the range of consumer specific needs. These formulations have to be individually formulated and are typically complex formulae containing a mixture of different dye compounds. As a result the manufacture of such product ranges can be costly and complex.
However, despite the fact that commercial hair dyeing products have been available for many years, the products still exhibit a number of consumer-related deficiencies.
Typically permanent hair dye products will contain an alkali, typically a source of ammonia. This serves the purpose of swelling the hair allowing the entry of the dye precursor molecules into the hair and also improves the lightening effect of the oxidising agent, which is typically hydrogen peroxide. However, ammonia is also volatile and its associated odour is extremely unpleasant to the consumers' of such products, particularly as these hair dye products are used in close proximity to the nasal region. Hence, it would be highly desirable to provide an oxidative hair colouring and/or bleaching composition, which delivers the consumer required lightening level and colour, but which has reduced or eliminated the detectable ammonia odour.
In fact another deficiency area in current hair colouring products is the provision of hair colouring products which deliver the required hair lightening effect. Delivering the required level of lightening is particularly important in order to provide the full range of colour shades demanded by the consumer, especially for blonde shades and grey coverage. Such products pose particular difficulties to the manufacturer, as they usually require the use of high levels of oxidising agent and ammonia in order to deliver the required lightening effect. However, in additional to the problems associated with the presence of high levels of ammonia in these products, as discussed herein above, the presence of these high levels of ammonia and/or oxidizing agent also affect the condition of the hair and may in some cases induce mild skin irritation on the scalp. In particular, the hydrophilicity of the hair surface is increased during the colouring process, which alters the sensory perception of the hair and its overall manageability during, immediately after colouring and during the subsequent wash and styling cycles until the next colourant application. Hence, it would also be highly desirable to provide an oxidative hair colouring and/or bleaching composition which delivers the required lightening and/or colour without unnecessary hair damage and or scalp irritation.
Moreover, in order to provide a product which the consumer can easily apply to the hair without dripping onto the skin, clothes or bathroom or salon surfaces, hair colourant products must be designed such that the applied composition has a certain required viscosity. This is either achieved by providing the dye composition (tint) and the oxidizing composition (developer) as so called thin-thin type liquid formulations which are thickened upon mixing, or, where at least one of the components, either the dye composition or the oxidizing composition, preferably the dye composition, is provided as a thickened formulation which thickens the total composition upon mixing or alternatively both dye and oxidizing compositions are thick prior to mixing (i.e. thick-thick-thick systems). These thickened compositions can be achieved by the use of a gel network system which provides the desired thickness to either the dye composition or the oxidizing composition or both compositions. Furthermore, such gel networks are highly desirable as they also provide additional benefits of a cream like texture, conditioner like feel and appearance, smooth rinse and improved hair feel. Such thickened gel network systems are described for example in WO2007/102119 and EP1878469. Amongst various surfactants which can be used to provide gel network systems, the preferred surfactants will ensure maximum compatibility with the variety of dyes, oxidizing agents, conditioning materials and so forth typically present in such compositions. Such surfactants may include for example alkyl ether phosphates as described in EP1669105.
Thin-thick-thick type systems are particularly desirable for certain retail markets as they facilitate easy mixing of the developer and tint components by the consumer prior to use in comparison to thick-thick-thick type systems. Such thin-thick-thick systems are typically provided with a thin oxidising component (developer) and a thick dye component (tint). The thin developer component also needs to meet a further number of requirements in addition to the ability to enable efficient mixing with the thick tint component such as peroxide stability and ensuring the desired rheology of the mixed composition is achieved and maintained.
A known means to achieve these needs is by the use of anionic surfactants in the developer composition, in particular sodium lauryl sulphate. However, whilst stable to peroxide and providing the desired rheology profile before and after mixing, these materials are not desirable as they are also known to cause skin irritation in certain circumstances. Alternative systems based upon non-ionic surfactant in particular ethoxylated non-ionic's do not however exhibit long term stability, when in contact with hydrogen peroxide, particularly at elevated temperatures which the products may be exposed to in transit or, storage or distribution in hot climates. Furthermore these products also do not maintain a constant rheology upon mixing with the tint, so that the viscosity increases over time and may result in the consumer being unable to readily squeeze the composition out of the container which typically is provided with a narrow tip.
The aforementioned problems are particularly severe when polymers such as associative polymers are also present in the developer composition. Associative polymers are often desirable in thin-thick-thick systems and are preferably incorporated into the developer composition in order to achieve preferred mixed viscosity upon mixing with the gel network containing tints. The resulting viscosity is often too high unless an anionic surfactant as described above is used. If the level of such a surfactant is reduced due to for example poor stability an unacceptable rheology rise will result.
Hence it would be desirable to provide the consumer with a hair colorant product, which in addition to delivering the required lightening, colour deposition, has the required rheology and viscosity prior and after mixing such that it can be readily utilised by consumers and does not raise any skin irritation. It would also be desirable to provide a composition which has a gel network structure so as to deliver the associated cream like texture of such systems.
It has now been surprisingly found that oxidative hair colouring compositions comprising a developer component comprising at least one oxidizing agent, a C6 to C16 alkyl glucoside in combination with a tint component comprising an anionic surfactant selected from C8-30 alkyl phosphate, alkyl ether phosphates or mixtures thereof and a C14-C30 fatty alcohol can provide the desired pre and post mixing rheology requirements and preferably does not raise any skin irritation.